In order to obtain molded articles from resins or rubbers, molding is carried out after a die is filled with resin or rubber materials, and usually the inner surface of the die is previously coated with a mold releasing agent before filling.
As the mold releasing agent, there are waxes such as a paraffin wax and a polyethylene wax, silicones such as a polydimethylsiloxane oil and a silicone resin, organic compounds such as a glycol, a derivative of fatty acid and a perfluoroalkyl group-containing compound, and inorganic compounds such as mineral oil, talc and mica, which are used in the form of dispersion or solution in water or an organic solvent.
The above-mentioned mold releasing agents are usually applied every time of the filling. It is desired that a mold releasing agent having a lengthy life is developed to decrease the number of steps of production process from the viewpoint of workability. Also since the mold releasing agent is applied every time of the filling, there occurs a problem of contamination of a die due to deposition of the mold releasing agent, and a degree of contamination is large particularly in case of the wax type mold releasing agent. Further the reason why the coating is necessary every time of the filling is that basically there is transfer of the mold releasing agent to the molded article, which causes poor finishing such as stickiness of the molded article and coating failure and adhesion failure on the molded article in the succeeding steps. Therefore the molded articles are rinsed with an organic solvent such as trichloroethane after molding. Particularly the silicone type mold releasing agent is apt to cause the coating failure and adhesion failure.
Also in case of making molded articles of polyurethane foam, there is a drawback such that cells on surface become rough at the time of molding. This is observed remarkably particularly in case of using the silicone oil as the mold releasing agent.
Various mold releasing agents have been developed to eliminate the above-mentioned drawbacks. Examples are a mixture of phosphate having a perfluoroalkyl group of 4 to 20 carbon atoms or its salt with a silicone oil (JP-B-23270/1978 and JP-B-23271/1978), a mixture of phosphate having a perfluoroalkyl group of 4 to 20 carbon atoms or its salt with a silicone varnish (JP-B-48035/1982), a mixture of a perfluoroalkyl group-containing polyether compound with a silicone oil (JP-B-32513/1984) and the like. Those mold releasing agents are preferable and excellent in mold releasing property and have a life longer than that of conventional ones. Further the mold releasing agent prepared by using the mixture of the perfluoroalkyl group-containing polyether compound and the silicone oil has almost no effect on secondary processability with respect to most of high molecular compounds. However even those mold releasing agents cannot satisfy the mold releasing property and life which have been required in view of the high molecular compound molded articles having complicated shape and large size.
As a mold releasing agent of cured film forming type having a longer life, JP-B-39804/1991 discloses a mold releasing agent containing a ladder polymer of a perfluoroalkyl group-containing acrylic polymer and organosilsesquioxane. That mold releasing agent is excellent in initial mold releasing property and its life is made longer to a certain extent. However since strength of the cured film is not sufficient, a desired life cannot be obtained.
Also JP-B-11605/1991 discloses a mold releasing agent containing polydimethylsiloxane, an alkoxysilane represented by the formula: EQU (Z.sup.1 O).sub.u SiZ.sup.2.sub.4-u
(wherein Z.sup.1 is methyl, ethyl, propyl or methoxyethyl, Z.sup.2 is a monovalent hydrocarbon group having 1 to 4 carbon atoms or a halogenated hydrocarbon group having 1 to 4 carbon atoms, u is 3 or 4) or its oligomer product prepared through partial hydrolysis and condensation, and a metal alkoxide such as tetraalkyl titanate. However this mold releasing agent is also not sufficient in the mold releasing property and the secondary molding processability.
The present invention was made to solve the above-mentioned problems, and an object of the present invention is to provide a mold releasing agent having excellent mold releasing property and a longer life, giving excellent surface finishing of molded articles and having no effect on secondary processability such as coating and adhesion of the molded articles.